Abstract: This study was conducted in 2014 to evaluate the effect of sulfur granular fertilizer, Rhizobium and Thiobacillus bacteria on yield and seed oil content of soybean (var. Williams) in Moghan plain, located in the northeast of Iran, Ardabil province. The experiment was designed based on randomized complete block (RCBD) with three replications. Treatments include sulfur fertilizer at four levels (zero, 200, 400 and 800 kg ha-1), Rhizobium and Thiobacillus bacteria both on two levels (seeds inoculation and control). The results showed that use of sulfur and inoculation with Rhizobium were increased the number of soybeans pods per plant. The interaction between sulfur and Rhizobium was significant and caused the soybeans 1000 seed weight increase. Yield and seed oil content was also influenced positively by all of these treatments. According to the results, it seems that using granulated sulfur with Thiobacillus as solubilizing bacteria and seeds inoculation with Rhizobium can increase yield and oil content of soybean and they are advisable.